Probability and variance-based stochastic design optimization of a radial compressor concerning fluid-structure interaction

Since the engineering of turbo machines began the improvement of specific physical behaviour, especially the efficiency, has been one of the key issues. However, improvement of the efficiency of a turbo engine, is hard to archive using a conventional deterministic optimization, since the geometry is not perfect and many other parameters vary in the real approach. In contrast, stochastic design optimization is a methodology that enables the solving of optimization problems which model the effects of uncertainty in manufacturing, design configuration and environment, in which robustness and reliability are explicit optimization goals. Therein, a coupling of stochastic and optimization problems implies high computational efforts, whereby the calculation of the stochastic constraints represents the main effort. In view of this fact, an industrially relevant algorithm should satisfy the conditions of precision, robustness and efficiency. In this paper an efficient approach is presented to assist reducing the number of design evaluations necessary, in particular the number of nonlinear fluid-structure interaction analyses. In combination with a robust estimation of the safety level within the iteration and a final precise reliability analysis, the method presented is particularly suitable for solving reliability-based structural design optimization problems with ever-changing failure probabilities of the nominal designs. The applicability for real case applications is demonstrated through the example of a radial compressor, with a very high degree of complexity and a large number of design parameters and random variables

Higher-dimensional normalisation strategies for acyclicity

We introduce acyclic polygraphs, a notion of complete categorical cellular model for (small) categories, containing generators, relations and higher-dimensional globular syzygies. We give a rewriting method to construct explicit acyclic polygraphs from convergent presentations. For that, we introduce higher-dimensional normalisation strategies, defined as homotopically coherent ways to relate each cell of a polygraph to its normal form, then we prove that acyclicity is equivalent to the existence of a normalisation strategy. Using acyclic polygraphs, we define a higher-dimensional homotopical finiteness condition for higher categories which extends Squier's finite derivation type for monoids. We relate this homotopical property to a new homological finiteness condition that we introduce here.Comment: Final versio

Bericht des Nationalen Referenzzentrums für gramnegative Krankenhauserreger

Im Zeitraum vom 1. Januar 2022 bis zum 31. Dezember 2022 gab es im Nationalen Referenzzentrum (NRZ) für gramnegative Krankenhauserreger 9.548 Einsendungen von Bakterienisolaten. Dies entspricht einem Anstieg von fast 12 % im Vergleich zu 2021 und übertrifft das Vor-Pandemieniveau von 2019 (n = 9.369). Die Anzahl der Einsendungen lag bei durchschnittlich 796 Einsendungen pro Monat, die Isolate stammten aus 301 mikrobiologischen Laboren in Deutschland. Die Zahl der einsendenden Labore nahm im Vergleich zum Vorjahr (n = 283) ebenfalls zu. Wie das Epidemiologische Bulletin 27/2023 ausführt, stieg zudem Die Anzahl der Carbapenemase-Nachweise bei den bearbeiteten Isolaten stieg zudem auf den höchsten jemals im NRZ beobachteten Anstieg.Peer Reviewe

Homotopy bases and finite derivation type for Schutzenberger groups of monoids

Given a finitely presented monoid and a homotopy base for the monoid, and given an arbitrary Schutzenberger group of the monoid, the main result of this paper gives a homotopy base, and presentation, for the Schutzenberger group. In the case that the R-class R' of the Schutzenberger group G(H) has only finitely many H-classes, and there is an element s of the multiplicative right pointwise stabilizer of H, such that under the left action of the monoid on its R-classes the intersection of the orbit of the R-class of s with the inverse orbit of R' is finite, then finiteness of the presentation and of the homotopy base is preserved.Comment: 24 page

Deformations processes at the Fonualei Rift and1Spreading Center from local seismicity

The Fonualei Rift and Spreading Center (FRSC) accommodate space in an east-west direction between the Niuafo'ou microplate and the Tonga plate. The current deformation process at the southern end of the FRSC is not fully understood yet. In December 2018 we deployed a network of 16 ocean bottom seismometers at the southern termination of the FRSC. During 32 days we estimated relative hypocenter locations of 440 earthquakes with moment magnitudes between 0.2 and 3.9. Focal mechanisms for 6 stronger events indicate normal faulting. Seismicity is mostly concentrated along the spreading axis of the FRSC. We also observe the absence of seismicity on the high standing rift flanks and generally absence of seismicity of the surrounding region. Based on comparisons with other extension systems, we discuss the possible similarities of seismicity patterns and the resulting tectonic deformation process at the southern end of the FRSC. The FRSC shows strong similarities to known mid-oceanic ridges. Rift systems, however, show differences in spatial seismicity distribution. Based on the seismic data presented and comparisons with other systems, the currently dominant process at the southern FRSC can be considered to be spreading

Probabilistic machine learning for pattern recognition and design exploration

The following thesis deals with the development of new probabilistic machine learning models with a focus on efficiency, flexibility, applicability, scalability and high prediction accuracy. Therefore, learning tasks from the areas of regression, classification, image classification, time series as well as the representation of spatial and / or temporally correlated quantities are examined. In order to achieve these goals and in addition to the development of the models themselves, their interaction to the field of data generation is also investigated. The calculable uncertainty of the probabilistic models is used to obtain the maximum information gain with as few data points as possible. This methodology is also used for the efficient solving of optimization problems. Besides obtaining an accurate approximation model of the data, a deeper understanding of the correlations between input and output is desired, therefore the topic of sensitivity analysis is a further part of this work. The developed probabilistic models are used to evaluate the number of calculations needed to estimate the sensitivities as efficiently as possible, even for correlated inputs

For Groups the Property of Having Finite Derivation Type is Equivalent to the Homological Finiteness Condition FP3

The homological finiteness property FP 3 and the combinatorial property of having finite derivation type both are necessary conditions for finitely presented monoids to admit a finite convergent presentation. For monoids in general, the property of having finite derivation type is strictly stronger than the property FP 3 . Here we show that for groups these two properties are equivalent. The proof exploits a result of [6], which states that a group G, which is given through a finite presentation hX; Ri, has finite derivation type if and only if the ZG-module of identities among relations that is associated with hX; Ri is finitely generated. We also give a new proof for this result which is much simpler than our original proof. AMS Math. Subj. Class.: 20F05,20J05,20M05. 1 Introduction In many instances rewriting systems that are convergent, that is noetherian and confluent, have been found to be quite useful for solving decision problems for algebraic structures effectively [13]. W..